Distillers, brewers and wineries pour millions of dollars into brand promotion on Twitter, Facebook and other social media, and industry critics contend they are not doing enough to prevent young consumers from receiving these messages.

"We're doing a deep dive on how they're using the Internet and social media," said Janet Evans, a lawyer with the FTC, which is conducting a year-long study due to be released by early summer. "We're focusing on underage exposure."

She would not elaborate on any potential recommendations that might come out of the study, which began in April 2012.

The FTC is reviewing data from 14 big producers, Evans said, including Beam Inc, the maker of Jim Beam, Diageo Plc, home to Johnnie Walker, and Constellation Brands Inc, which makes Robert Mondavi and Ravenswood wines.

The FTC report "is something we take seriously and place at high priority," said Karena Breslin, director for digital marketing at Constellation.

The FTC has made two requests for information since the study began, she said.

The regulatory agency has not said it intends to impose restrictions on liquor company social media advertising but it can make recommendations to the industry.

The FTC is empowered to file suit to ensure consumers are protected from deceptive marketing practices, Evans said, but she stressed that studies of this nature are meant to promote better self-regulation, not provide a basis for a case.

Industry executives say alcohol makers and distributors voluntarily adhere to the same industry-set standard for marketing to underage viewers on social media sites that the industry set for its ads on TV and other media. That requires that at least 71.6 percent of an audience consists of adults 21 and older.

"No one in their right mind would want to advertise to people who can't legally buy their product," said Frank Coleman, senior vice president for Distilled Spirits Council of the United States (DISCUS), the trade group that sets the industry's advertising codes.

Coleman also cited recent data showing the audiences for Facebook and Twitter are skewed heavily towards viewers who are above the legal drinking age.

"According to Nielsen's latest data, the demographic audience for Facebook is 83.5 percent 21 years and older, and for Twitter it is 85 percent," Coleman said.

In June 2011, DISCUS revised its code upwards to 71.6 percent from 70 percent, after the FTC recommended it review the standard to better reflect U.S. Census population data.

Industry critics, including David Jernigen, director of the Center on Alcohol Marketing and Youth at Johns Hopkins University, and Sarah Mart, research director of the advocacy group Alcohol Justice, contend the industry didn't go far enough and should raise the standard further.

Jernigen said it needs to be at least 85 percent to effectively protect youth, so there would be no more than 15 percent exposure to the underage drinking population.

"The industry says its self-regulating but it's ineffective and social media opens up a whole new set of problems because their ads are everywhere," said Mart.

Coleman said the group now requires members to install age-checking tools via instant messaging as a gateway to Twitter feeds and other branded Web platforms that ask the user for a birth date before admitting them.

In the first nine months of 2012, beer, wine and spirits manufacturers spent an estimated $35 million for paid Web display advertising, but industry executives estimate many millions more were spent on website creation, video production for platforms like Google's YouTube and social media marketing efforts.

"We've significantly adjusted more money to digital for online video, websites, Facebook and Twitter content," said Kevin George, global chief marketing officer for Jim Beam, which spends 30 percent of its media spend for online outlets, up from 10 percent in 2008, he said.

Many companies are expanding their digital staff. Wine maker Constellation hired Breslin three years ago to initiate digital marketing and now has a team of five reporting to her.

Many alcoholic beverage companies flocked to Facebook because it requires users to post their birth dates when signing up.

Last year Twitter partnered with Buddy Media to offer a screening tool that sends a direct message to fans who click on an alcoholic brand. The message sends the fan a link to a site that asks for date of birth.

Salesforce.com bought Buddy Media last June, which is now folding the platform into its marketing cloud portfolio.

Health advocates and industry critics are crying foul. "Facebook and other interactive platforms are poorly monitored and not well age-protected," said Jernigen of Johns Hopkins University. "Anyone can say they're 21 and click yes."